1. Field of the Invention
The present invention relates to a pneumatic tire more particularly to a run-flat tire improved in run-flat performance.
2. Description of the Related Art
Run-flat tires of which sidewall portions are reinforced with hard rubber have a crescent sectional shape and are disclosed in the laid-open Japanese patent applications JP-A-53-18104, JP-A-64-30809 and JP-A-4-154411. Those tires are designed to support tire loads under a flat condition by the rigidity, especially bending rigidity of the sidewall portions between the road surface and the wheel rim. As a result, it is difficult to avoid some deterioration in ride comfort under normal conditions, as well as a great increase in the tire weight and a resultant deterioration in dynamic tire performance.